Diagnostic methods and arrangements of the kind referred to above are used for monitoring networks including field bus systems.
Industrial networks connect different process systems such as field apparatus, controls and visualization. Field apparatus include especially sensors, actuators or drives. Controls are open loop or closed loop controls especially control units, controllers and computers having open loop control programs and closed loop control programs. Visualization includes especially display apparatus and display screens of the computers or mobile devices.
Industrial networks are field bus systems (for example, Profibus or Interbus) and systems, which are based on the ethernet, for example, Profinet. Two networks are coupled to each other or are separated from each other via a router.
Field bus systems include a network, at least one field apparatus as well as network infrastructure components, for example, repeaters and/or couplers. In field bus systems, the field apparatus are, as a rule, referred to as master and slaves. The masters can, without command, access common resources; whereas, the slaves can access these resources only when they are asked by a master.
Several servers and clients communicate with each other via the network. A server is a computer program which offers a service. In contrast, a client is a computer program which, in accordance with the server/client model, establishes a connection to a server via the network and exchanges information therewith. The server is capable, at any time, to react to the contact request of a client. A web browser is a client which establishes contact to a web server and requests a specific web page from this server and makes the web page available to an output unit for display.
A broadcast defines the characteristic in a network. A broadcast is a message wherein data packets are transmitted from one point to all subscribers of a network.
An SNMP (Simple Network Management Protocol) is a network protocol with which the subscribers of a network can be monitored and controlled.
In industrial networks, especially of field bus systems, different errors can occur, for example, invalid signal levels or invalid signal shapes which are caused by defectively operating or incorrectly configured process systems, electromagnetic disturbances or a line interruption. For this reason, industrial networks must be monitored wherefor different diagnostic apparatuses are known.
An arrangement for the diagnosis and/or parameterization of field apparatus integrated into a field system is disclosed in U.S. Pat. No. 7,082,340 and United States patent publication 2004/0098143. With this arrangement, the apparatus parameters of the field apparatus can be read out and/or can be transferred into the field apparatus as well as read out and/or apparatus parameters to be transmitted can be visibly displayed via an output unit.
However, it is a disadvantage that this arrangement is also an active bus subscriber for the diagnosis and therefore intervenes in the field bus which is not wanted by many system operators for diagnostic purposes.
Furthermore, it is disadvantageous that always only one field apparatus can be diagnosed with this arrangement. Several field apparatuses can only be monitored sequentially and therefore not at the same time and not continuously.
A method for diagnosing field apparatuses is known from German patent publication 102 52 892 A1 wherein a software agent is integrated onto a processor of a field apparatus which, with the occurrence of an error, outputs a field error announcement to the guidance system. Here, it is a disadvantage that an announcement as to the state of the field apparatus is only outputted to the guidance system when an error occurs.
In addition, both solutions presented up to now have the disadvantage that a manufacturer-specific evaluation software is needed which limits the application of use of these solutions.
Furthermore, to diagnose field bus systems, it is known to utilize so-called protocol analyzers. Protocol analyzers are, for example, telegram analyzers or bus monitors which comprise primarily interface component groups having a software corresponding thereto and wherewith the data packets (so-called telegrams), which are transmitted in a field bus, are evaluated. These interface component groups are, for example, PC plug-in cards or external adaptors with the external adaptors being connected to a computer via known interfaces, for example, a USB interface.
A computer-implemented diagnostic method for a field bus system and an arrangement corresponding thereto are known, for example, from United States patent publication 2008/0140874 wherein the transmitted data packets are detected, analyzed and stored. For analyzing, the currently detected data packet is compared to the previously stored data packet and the current state of the field bus system is derived. Here, it is, however, a disadvantage that this computer-implemented diagnostic method is an apparatus-specific and/or manufacturer-specific software which, in turn, significantly limits the application of use of these solutions. In addition, each field apparatus mostly has a large number of apparatus parameters whereby, in this solution, also the data quantities, which are transmitted, are very large.
It is also a disadvantage that this computer-implemented diagnostic method and the arrangement corresponding thereto are suitable only for monitoring one field bus system.
Furthermore, a diagnostic arrangement for a field bus system is known from U.S. Pat. No. 7,173,909 which, however, is tied into a higher-order application such as a visualization application. This higher-order application is integrated into a computer having an interface component group (for example, a PC plug-in card) in the form of software. Each diagnostic unit is electrically connected to the computer.
This suggested solution, however, has the disadvantage that the higher-order computer is separately electrically connected to each diagnostic unit and an updating of the diagnostic data of each diagnostic unit takes place sequentially on the computer. In this way, the updating of the diagnostic data of each diagnostic unit is shifted in time on the computer so that an error in a field bus system is not updated and displayed on the computer with its occurrence but is updated and displayed with a delay.
A diagnostic arrangement for a control and data transmitting system in automation technology is disclosed in German patent publication 197 31 026 C2. The diagnostic arrangement is connected via a connecting unit to a field bus system and via an interface to an ethernet. In this way, the respective control and data transmission systems can be connected to a computer via the ethernet. The computer has a network management and the interfaces transmit data between the respective field bus systems and the network management.
This solution, however, has disadvantages. In this solution too, an apparatus-specific software is needed for the network management whereby the readiness of use of this solution is significantly limited. In addition, because of the large data quantities, which are to be exchanged between the interfaces and the computer, the scope of use of this solution is limited by the bandwidth of the ethernet. Furthermore, no simultaneous access to the data by several computers is possible with this central arrangement in the form of the network management so that no decentralized diagnosis and/or diagnosis evaluation can take place. This access to the data is also carried out independently of each other and from different locations.